7,989 research outputs found
An overview of the Daya Bay Reactor Neutrino Experiment
The Daya Bay Reactor Neutrino Experiment discovered an unexpectedly large
neutrino oscillation related to the mixing angle in 2012. This
finding paved the way to the next generation of neutrino oscillation
experiments. In this article, we review the history, featured design, and
scientific results of Daya Bay. Prospects of the experiment are also described.Comment: 18 pages, 5 figures. An overview to appear in the Special Issue on
neutrino oscillations of Nuclear Physics
Optimal strategies for a game on amenable semigroups
The semigroup game is a two-person zero-sum game defined on a semigroup S as
follows: Players 1 and 2 choose elements x and y in S, respectively, and player
1 receives a payoff f(xy) defined by a function f from S to [-1,1]. If the
semigroup is amenable in the sense of Day and von Neumann, one can extend the
set of classical strategies, namely countably additive probability measures on
S, to include some finitely additive measures in a natural way. This extended
game has a value and the players have optimal strategies. This theorem extends
previous results for the multiplication game on a compact group or on the
positive integers with a specific payoff. We also prove that the procedure of
extending the set of allowed strategies preserves classical solutions: if a
semigroup game has a classical solution, this solution solves also the extended
game.Comment: 17 pages. To appear in International Journal of Game Theor
What influences the speed of prototyping? An empirical investigation of twenty software startups
It is essential for startups to quickly experiment business ideas by building
tangible prototypes and collecting user feedback on them. As prototyping is an
inevitable part of learning for early stage software startups, how fast
startups can learn depends on how fast they can prototype. Despite of the
importance, there is a lack of research about prototyping in software startups.
In this study, we aimed at understanding what are factors influencing different
types of prototyping activities. We conducted a multiple case study on twenty
European software startups. The results are two folds, firstly we propose a
prototype-centric learning model in early stage software startups. Secondly, we
identify factors occur as barriers but also facilitators for prototyping in
early stage software startups. The factors are grouped into (1) artifacts, (2)
team competence, (3) collaboration, (4) customer and (5) process dimensions. To
speed up a startups progress at the early stage, it is important to incorporate
the learning objective into a well-defined collaborative approach of
prototypingComment: This is the author's version of the work. Copyright owner's version
can be accessed at doi.org/10.1007/978-3-319-57633-6_2, XP2017, Cologne,
German
On Sub-ENSO Variability
Multichannel singular spectrum analysis (MSSA) of surface zonal wind, sea surface temperature (SST), 20° isotherm depth, and surface zonal current observations (between 1990 and 2004) identifies three coupled ocean–atmosphere modes of variability in the tropical Pacific: the El Niño–Southern Oscillation (ENSO), the annual cycle, and a mode with a 14–18-month period, which is referred to as sub-ENSO in this study. The sub-ENSO mode accounts for the near 18-month (near annual) variability prior to (following) the 1997/98 El Niño event. It was strongest during this El Niño event, with SST anomalies exceeding 1°C. Sub-ENSO peak SST anomalies are ENSO-like in structure and are associated with eastward propagating heat content variations. However, the SST anomalies are preceded by and in near quadrature with relatively strong remotely forced westward propagating zonal current variations, suggesting the sub-ENSO mode arises from the zonal-advective feedback.
The sub-ENSO mode is found to exist also in an intermediate complexity model (ICM) of the tropical Pacific. A heat budget analysis of the model’s sub-ENSO mode shows it indeed arises from the zonal-advective feedback. In the model, both ENSO and sub-ENSO modes coexist, but there is a weak nonlinear interaction between them. Experiments also show that the observed changes in sub-ENSO’s characteristics may be explained by changes in the relative importance of zonal and vertical advection SST tendencies
Proof for an upper bound in fixed-node Monte Carlo for lattice fermions
We justify a recently proposed prescription for performing Green Function
Monte Carlo calculations on systems of lattice fermions, by which one is able
to avoid the sign problem. We generalize the prescription such that it can also
be used for problems with hopping terms of different signs. We prove that the
effective Hamiltonian, used in this method, leads to an upper bound for the
ground-state energy of the real Hamiltonian, and we illustrate the
effectiveness of the method on small systems.Comment: 14 pages in revtex v3.0, no figure
The prevalence of cubital tunnel syndrome: A cross-sectional study in a U.S. metropolitan cohort
BACKGROUND: Although cubital tunnel syndrome is the second most common peripheral mononeuropathy (after carpal tunnel syndrome) encountered in clinical practice, its prevalence in the population is unknown. The objective of this study was to evaluate the prevalence of cubital tunnel syndrome in the general population. METHODS: We surveyed a cohort of adult residents of the St. Louis metropolitan area to assess for the severity and localization of hand symptoms using the Boston Carpal Tunnel Questionnaire Symptom Severity Scale (BCTQ-SSS) and the Katz hand diagram. We identified subjects who met our case definitions for cubital tunnel syndrome and carpal tunnel syndrome: self-reported hand symptoms associated with a BCTQ-SSS score of >2 and localization of symptoms to the ulnar nerve or median nerve distributions. RESULTS: Of 1,001 individuals who participated in the cross-sectional survey, 75% were women and 79% of the cohort was white; the mean age (and standard deviation) was 46 ± 15.7 years. Using a more sensitive case definition (lax criteria), we identified 59 subjects (5.9%) with cubital tunnel syndrome and 68 subjects (6.8%) with carpal tunnel syndrome. Using a more specific case definition (strict criteria), we identified 18 subjects (1.8%) with cubital tunnel syndrome and 27 subjects (2.7%) with carpal tunnel syndrome. CONCLUSIONS: The prevalence of cubital tunnel syndrome in the general population may be higher than that reported previously. When compared with previous estimates of disease burden, the active surveillance technique used in this study may account for the higher reported prevalence. This finding suggests that a proportion of symptomatic subjects may not self-identify and may not seek medical treatment. CLINICAL RELEVANCE: This baseline estimate of prevalence for cubital tunnel syndrome provides a valuable reference for future diagnostic and prognostic study research and for the development of clinical practice guidelines
The Algorithmic Origins of Life
Although it has been notoriously difficult to pin down precisely what it is
that makes life so distinctive and remarkable, there is general agreement that
its informational aspect is one key property, perhaps the key property. The
unique informational narrative of living systems suggests that life may be
characterized by context-dependent causal influences, and in particular, that
top-down (or downward) causation -- where higher-levels influence and constrain
the dynamics of lower-levels in organizational hierarchies -- may be a major
contributor to the hierarchal structure of living systems. Here we propose that
the origin of life may correspond to a physical transition associated with a
shift in causal structure, where information gains direct, and
context-dependent causal efficacy over the matter it is instantiated in. Such a
transition may be akin to more traditional physical transitions (e.g.
thermodynamic phase transitions), with the crucial distinction that determining
which phase (non-life or life) a given system is in requires dynamical
information and therefore can only be inferred by identifying causal
architecture. We discuss some potential novel research directions based on this
hypothesis, including potential measures of such a transition that may be
amenable to laboratory study, and how the proposed mechanism corresponds to the
onset of the unique mode of (algorithmic) information processing characteristic
of living systems.Comment: 13 pages, 1 tabl
Electrical detection of magnetic skyrmions by non-collinear magnetoresistance
Magnetic skyrmions are localised non-collinear spin textures with high
potential for future spintronic applications. Skyrmion phases have been
discovered in a number of materials and a focus of current research is the
preparation, detection, and manipulation of individual skyrmions for an
implementation in devices. Local experimental characterization of skyrmions has
been performed by, e.g., Lorentz microscopy or atomic-scale tunnel
magnetoresistance measurements using spin-polarised scanning tunneling
microscopy. Here, we report on a drastic change of the differential tunnel
conductance for magnetic skyrmions arising from their non-collinearity: mixing
between the spin channels locally alters the electronic structure, making a
skyrmion electronically distinct from its ferromagnetic environment. We propose
this non-collinear magnetoresistance (NCMR) as a reliable all-electrical
detection scheme for skyrmions with an easy implementation into device
architectures
Electronic structure of MgB: X-ray emission and absorption studies
Measurements of x-ray emission and absorption spectra of the constituents of
MgB are presented. The results obtained are in good agreement with
calculated x-ray spectra, with dipole matrix elements taken into account. The
comparison of x-ray emission spectra of graphite, AlB, and MgB in the
binding energy scale supports the idea of charge transfer from to
bands, which creates holes at the top of the bonding bands and
drives the high-TComment: final version as published in PR
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